221 Papers for 5/4

Mark Andrew SMITH (masmith@cs.ucsd.edu)
Wed, 3 May 2000 23:47:13 -0700 (PDT)


Sprite is another example of a distributed operating system in which the
designers are re-evaluating some basic OS assumptions and constraints that
have existed in the past, but that are no longer necessarily true due to
rapid hardware development and improvement. Some such hardware the
designers of Sprite mentions include networks, large memories and
multiprocessors. In order to leverage networks, Sprite's main technique is
process migration in which a process can explicitly be migrated from one
machine to another with lesser load. All computation results are the same
after being migrated. In order to leverage multiprocessors, shared memory
is implemented. This is particularly useful for multiprocessors because if
a task is to be decomposed in a multiprocessor machine, pieces of that
task in memory need to communicate quickly between each processor. Shared
memory allows for this sharing without having to copy memory around and
incur the overhead of consistency maintenance. This is also made possible
by the fact that larger memories are becoming available, so it is becoming
plausable that much of a process, and in fact multiple processes and their
data can be kept completely in memory.


This paper describes a distributed system that attempts to implement two
major changes with respect to how traditional distributed systems operate.
First, most nodes on the network have no secondary storage and therefore,
most network traffic is file access. Secondly, they use a general purpose
network IPC facility to do this when one would expect a very specialized
IPC in order to optimize file transfer over the network. Message passing
occurs in fixed size synchronous messages for ease of programming. There
is a workaround for larger messages using MoveTo and MoveFrom. This was
done in order to optimize the common case which is the small message.
Performance detaisls in the Measurements section are pretty weak, could
use some comparisons to other systems.